Cold cathode discharge tube



Sept. 8, 1959 M. w. WALLACE COLD CATHODE DISCHARGE TUBE Filed Oct. 7,1954 INVENTOR M/L/VEQ M WALZACE AGENT United States Patent 6 90 5% COLDCATHODE DIscHARGE TUBE Milner W- W l wes uq d, as ignor t nt nationalTelephone and Telegraph Corporation, Nutsy I i-"? s rp ates 9f MenardApplication Qctober 7, 1954, Serial No. 460,877 Claims L 315-34 Thisinvention relates to electron switching and counting devices and moreparticularly to multigap cold cathode discharge tubes for use in suchdevices capable of'effectively performing both counting and triggeringfunctions.

In multigap tubes heretofore proposed for switching andcountin'g'devices, an anode and several cathodes areprovided to 'form anumber of cathode-anode gaps. In the use of these tubes, it is desiredthat the gaps discharge in a given order. It is also desirable that thedischarge transfer reliably from one gap to another gap in some definiteprescribed sequence. Such a multigap tube has been prepared and isdescribed in my issued US. Patent 2,642,548. When such tubes arecascaded for purposes of sealer counting or frequency division, it isnecessary to utilize theoutput pulse'from one tube to trigger thesucceeding tube. A tube for such triggering has been described by G. H.Hough and D. S. Ridler in Multicathode Gas Tube Gounters appfi'ared inElectrical Comm sa isn S t mbe 1 0' However, neither of these prior artdevices, as described in the above-mentioned patent and publication, canbe us sr Psu s of i ss i f am triggering b hem el e A sent is btfrequency di si o ssalsr o nt n it s nsas s #6 f e the ou t Pu s m a msti sr Id ss sr us a ssss ti for mpl '4 U-S- 2s6 248i t a sing 9? m iss hfis t ig bs s st bsd in t e s p s ted P bli at n 1 tr ube s requ red inrde is mplify O u m' h counter tube. The output from the cbunter tube,after bei a lifi d b e t ia e? tu e is thsri te is o h sa er u s sm thee s. s q la r trigger ts if sm t re in us e s s to s st r tub and r r band ultimately to a mechanical register or other device'de; p n u on theappli a ig desi e hu w r an extensive series of frequency divisien orsealer counting is us d. ma tub s ma be isa rsd' fsr P p s p p rfq m n bth h ss nt and r g n fu t sr' queutly, qu reme fa my tub m k s f iultace s side a i l m s 't s he i' s sn ntm u e abora e W in and pro u q prb ems .I use the te ms ha n in wit hin a d st ppin e e n a es en ia yynq mq sg e n i re stricted herein to utilization of the output pulse ofa counting tube to activate a second tube or'iother device.

On o the o je t 9f the P es m nna t pr vide a cold cathode gas-firedcounting and switching tube capable of providing a triggering outputpulse of much h he pow th n 1 .Q a sbl qm known 's s and switching gastubes. v 4 v I Another object is to provide a tube performing bothcounting and triggering functions wherein output'circnit requirementsofpreviously known counting and trigger tube combinations areeliminated.

An additional object is to provide a novel type of directional cathodefor the purposes of performing the foregoing counting and triggeringfunctions.

One of the features of .this invention is that the counting functionpreviously performed by one tube and the ice 2v r gerin fun i n re upsrfsrmsd y- 1, e mars other'tubes'are cooperatively and coactivelyinterrelated so that'both functions are performed within the envelope ofa single gas discharge tube.

' It is a further feature of this inyention that by eliminat ingtheloading efiect of the output cir cuit' of previously known counting; andtrigger tube combinations, the counting' function can be performed morerapidly under less criticalcir'c'uit conditions, and the output frornthecounting tube is rendered suflicient to activate asueeeeu ingcountertube without prior amplification by a trigger tubef It is anotherfeature of this tube that a new electrode comprising a single loop ofwire or a multi-looped spiral with its free end disposed to be primed bya discharge occurring in an adjacent cathode-anode gap is provided. Theattached spiral portion serves to maintain the cathode g o Theabove-mentioned and other features and objects of this invention willbecome more apparent by reference to the following description taken inconjunction with the accompanying drawings wherein:

Fig. 1 is an elevational view in section of a multigap tube according tothe present invention;

Fig.2 is a plan view partly in section of the tube shown in Fig. 1;

FigsfZA and 2B are sectional views taken along the lines 2A2A and ZBfZB,respectively, of Fig. l;

Figs 3 and 3A 'show'views 'in perspective of two em bodiments of a newtype of directional electrode; and Fig 4 is a schematic View of thebasic circuit of the 7 tubeof this invention.

Referring to Figs. 1, 2, 2A and 2B of the drawing, the tube comprises anenvelope 1, preferably of glass or quartz, mounted in a base 2 which isprovided with terminals 3 for reception in a socket. The terminals 3 areconnected by leads 4 through the envelopel to corresponding electrodesof the tube. The base and envelope are secured together by cement 5.There is present a set of stepping glow cathodes 5 equispaced in aci'rcl'llar or other reentrant array and facing the communicatingpassageway/s7 present "in the base of the cup-shaped first anode}. Thus,in a tube withfive counting positions, as illustrated in these figures,there would be ten of these cathodes 6. Each cathode 6 is providedpreferably With a directional preference mechanism such as a Wire tail 9for purposes of directing the discharge. A control plate or shield hasnot been shown, although one may be provided, as it not consideredessential for the functioning ofthis tube." These cathodes 6 areconnected electrically mehanically in two sets at their supportinginsulating bases 10, made of a material such as mica, so that adjacentcathodes are not connected in the same set, but are in alternatingarrangement. These connections are repreeented by bands (11 and 12 whichalso act as stops for the vertical location of the cathodes. Each set'of these, cathodes is connected through a lead 13 to the tube base 2.This portion of the tube as described may be operated as a countingdevice in a manner similar to that described in my issued U.S. Patent2,642,5{gi}. For obtaining the desired output for subsequent triggeringof similar counting tubes or other devices following in sequence, anadditional set of gaps 14 is provided. These gaps are formed by outputcathodes 15 and a common second anode' 1 6. An eyelet 1701 similarmechanical device is used to attach the disk-shaped anode 16 to thecentral conductive post 18 and also insureelectrical contact of anode 16 therewith. An insulating sleeve 19 about the conductive post 18' isused to'prevent' discharges between this postand other conductingmembers within the tube envelope. Cathodes 15 are supported on a micabase 20 and connected tothe tube terminals'by means of conductivemembers 21 and leads 4. While for certain applications common anodes 6and 16 may be combined into one anode, I generally prefer to use twoseparate common anodes. For the fiveposition switching tube illustrated,I have shown five of these output cathodes 15. These cathodes arepositioned so that their tips are adjacent to or overlying thecommunicating passageways 7 in anode 8. For such a fiveposition tube,five of these passageways 7 may be provided: one over each of one groupof electrically connected stepping glow cathodes 6. This group ofcathodes may serve either as the transfer set, to which input pulses areapplied, or as the storage set, depending on external connection of thetube.

In the tube illustrated, the stepping glow cathodes have been shown asprovided with a directional preference mechanism, and divided into twogroups of storage and transfer cathodes. For each cathode of one groupof these stepping glow cathodes, an output cathode capable of deliveringa triggering pulse has been provided. It will be apparent to thoseskilled in this art that for simple counting, for example, such adecimal counting, more than one output cathode per counting tube may notbe required. Where the stepping glow cathodes are not provided with adirectional preference mechanism the sequential stepping operation maybe obtained by means of external circuitry. For such a tubeconstruction, the number of output cathodes may vary up to as much asthe total number of stepping glow cathodes. Where the stepping glowcathodes are directional and divided into two groups as illustrated inthe figures, the maximum number of output cathodes will not ordinarilyexceed the total number of stepping cathodes present in one group only.

In Fig. 3 is shown an enlarged perspective view of a novel type ofcathode electrode 6a particularly suitable as a directional electrode.This electrode comprises a single-loop 22 of wire with the outer end 23of the cathode disposed to direct the discharge occurring in an adjacentcathode to its own attached portion. It thereby serves to be primed bythis adjacent discharge. The design of the electrode is such that thesmaller portion 24 of the spiral will serve to maintain the cathode glowand in turn serve to prime the outer end 23 of the next cathode. In Fig.3A is shown an enlarged view in perspective of a multiple-looped cathode6b. The several loops 22a forming the cathode structure are in spiralshape and substantially within the same plane. The spiral is formedpreferably in a closed form, with no spacing present between adjoiningcoils. Such a spiral arrangement oifers advantages over a helicalspring-shaped cathode in that deionization times are hastened. Therebyan input pulse switching rate as high as 20-30 kilocycles per second maybe attained. The more conventional cathodes are capable of input pulserates of only about 2-5 kilocycles per second. The ability to switch atthe higher rates broadens the useful field of application of thesedevices, as for example in the field of color television.

In Fig. 4 is shown a schematic manner of depicting the tube in acircuit. It will be seen that for proper operation of the tube, thevoltages appearing on the elements of the tube should be in thefollowing relationship:

where K refers to a cathode in set A of cathode 6, K refers to a cathodein set B of cathode 6, A is anode 8, K is output cathode i5 and A isoutput anode 16.

The operation of this tube is as follows, assuming K, to represent thetransfer electrodes, i.e., those electrodes whose discharge is activatedby a pulse input, and K represents the storage electrodes, thoseelectrodes whose discharge occurs in the absence of a pulse. In Fig. 4the communicating passageways have been shown as located over thetransfer electrodes. When a particular will fire only during the inputpulse.

transfer cathode 6 is conducting, the corresponding gap defined bycathode 15 and anode 16 are primed. The voltage on output gaps 14 isless than the normal striking voltage and greater than the primestriking voltage so that these gaps will be fired when they are primed.This results in a voltage rise in the output cathode resistor 25. Thegap remains conducting until the next output gap is fired. Where it isdesired to obtain a short output pulse, i.e., one that is less than theinput pulse period, the cathode resistor 25 may be made large enough toextinguish the gap. Alternatively, the input pulse may be applied toanode 16 as well as to the input set of cathode 6, and the supplyvoltage reduced so that the output gap It is also possible to arrangethe tube so that the count may be read by looking at the position of theglow and yet obtain a short output pulse. This may be accomplished bymodifications in the external circuitry or by having the counting gapsvisible.

While I have shown several possible cathode-anode assembly arrangementsin Figs. 1 and 2, it will be clear that many other arrangementsutilizing the simple cathode anode relationship and the assemblyfeatures of the present invention are possible. The cathodes 6, forexample, may be arranged in any type of re-entrant array desired,regular or irregular, so long as the anode S is spaced equally from eachof the cathodes 6 and one group thereof is properly positioned withrespect to communicating passageways 7. Also, the cathodes 6 used may beformed in various shapes. For the attainment of high switching rates, aswell as for simplicity of construction, the cathode embodiments 6a and6b shown in Figs. 3 and 3A, respectively, are preferred. These cathodesmay be conveniently fabricated from a tungsten wire as thin as .003 inchin diameter or from nickel or molybdenum wires of approximately .006inch in diameter. Where directed sequential firing is not required, oris provided by external circuitry, the so-called tails 9 of cathodes 6may be omitted. Thereby all cathodes 6 function as storage cathodw andhalf their number may be eliminated leaving an equal quantity of storagecathodes 6 and output cathodes 15. Where greater directivity is desired,the cathodes 6 may be fabricated in a cup-shaped manner, the glowdischarge being thereby confined essentially to the hollow portion ofthe cathode. Such a structural arrangement will not provide as rapid adeionization time as that obtained with cathodes 6a and 612. Also, it isconsidered possible by suitable modifications in the external circuitryand in the structural arrangement of the tube to provide cathode-anodegaps by using a single common cathode and multiple anodes.

The gaseous atmosphere preferred for the tube is a mixture of neon,argon, and hydrogen, the percentages of which may be varied widelydepending upon the gas pressure, the electrode voltages, the electrodegeometry of the tube, and the breakdown voltage point desired. Wherehydrogen gas is used in small percentages, the hydrogen acceleratesdeionization and is therefore desirable inasmuch as the counting speedlimitations in a gas discharge device are set to a large extent by thedeionization properties of the gaseous filling. Similarly, the tubegeometry affects the degree of ionization coupling, i.e., the difierencein break-down potential of a gap measured in the unprimed and primedconditions. Generally, the amount of hydrogen preferred is between 5 and10%. Argon is used principally to reduce the breakdown voltage point,and the amount present is not-critical. The percentage of argon ispreferably between about 1 and 3%. The remaining component of the gasmixture is neon. Although the over-all gas pressure is not critical,relatively high pressures in the neighborhood of millimeters of mercuryare preferred. The higher pressures generally favor more rapiddeionization and also give a wider spread between normal striking andmaintaining voltages.

I have described above the principles of my in;

vention in connection with specific apparatus, it is to be clearlyunderstood that this description is made by way of example only and notas a limitation to the scope of my invention as set forth in the objectsthereof and in the accompanying claims.

I claim:

1. A discharge device comprising a hermetically sealed envelopecontaining a gaseous atmosphere, a first anode, an array of steppingglow cathodes spaced apart from said anode to provide a series ofcathode-anode gaps, a second anode, at least one output cathodegalvanically separated from said glow cathodes and spaced apart fromsaid second anode to provide at least one output cathode-anode gap, saidoutput cathode-anode gap being in a coactive relation to a selected oneof said series of cathode-anode gaps and capable of being dischargedupon occurrence of a discharge in said selected one.

2. A discharge device according to claim 1 including means electricallyconnecting said stepping glow cathodes in two groups with the cathodesof the two groups in alternate relation.

3. A discharge device according to claim 1 wherein said first anode isinterposed between said array of stepping glow cathodes and said outputcathodes, said anode including communicating means between a steppingglow cathode and an output cathode.

4. A discharge device comprising a hermetically sealed envelopecontaining a gaseous atmosphere, a first anode, an array of steppingglow cathodes spaced apart from said anode to provide a series ofcathode-anode gaps, means electrically connecting said stepping glowcathodes in two groups with the cathodes of the two groups in alternaterelation, a second anode, a plurality of output cathodes galvanicallyseparated from said glow cathodes and spaced apart from said secondanode to provide a plurality of output cathode-anode gaps, said outputcathode-anode gaps being in a coactive relation to respective selectedones of one group of said series of cathode-anode gaps and capable ofbeing discharged upon occurrence of a discharge in said selected ones.

5. A discharge device according to claim 4 wherein said stepping glowcathodes include means defining a directional preference mechanism.

6. A discharge device according to claim 5 wherein said means defining adirectional preference mechanism comprise a looped spiral wire with itsouter end disposed to be primed by a discharge at an adjacent glowcathode, the loops of said spiral being maintained substantially withinthe same plane.

7. A discharge device according to claim 4 wherein all said steppingglow cathodes include means defining a directional preference mechanismcomprising a multilooped spiral whose loops all lie substantially in thesame plane and whose outer end is disposed to be primed by a dischargeat an adjacent glow cathode and wherein said first anode is interposedbetween said array of stepping glow cathodes and said output cathodes,said first anode including communicating means between the cathodes ofone group of electrically connected stepping cathodes and respectiveoutput cathodes.

8. A discharge device comprising a hermetically sealed envelopecontaining a gaseous atmosphere, a first anode, a re-entrant array of aneven number of stepping glow cathodes spaced apart from said anode toprovide a series of cathode-anode gaps, means electrically connectingsaid glow cathodes in two groups with the cathodes of the two groups inalternate relation, a second anode, a plurality of output cathodesgalvanically separated from said glow cathodes equal in number to thestepping glow cathodes of one electrically connected group of saidstepping glow cathodes, said output cathodes being spaced apart fromsaid second anode to provide a plurality of output cathode-anode gaps,said second anode being interposed between said stepping glow cathodesand said output cathodes, said first anode having communicating meansdisposed between the cathodes of one group of electrically connectedstepping cathodes and respective output cathodes to provide a coactiverelationship between one group of the series of stepping cathode-anodegaps and respective output cathode-anode gaps whereby said outputcathode-anode gaps are capable of being discharged upon occurrence of adischarge in said corresponding cathode-anode gaps defined by one groupof stepping glow cathodes and said first anode.

9. A discharge device according to claim 8, wherein said first anode isa cup-shaped member having a substantially flat base section and whereinsaid communicating means in said first anode comprise passageways inreentrant array in said base positioned adjacent the cathodes of onegroup of electrically connected stepping glow cathodes.

References Cited in the file of this patent UNITED STATES PATENTS2,553,585 Hough May 22, 1951 2,687,496 Wales Aug. 24, 1954 2,690,525Koehler Sept. 28, 1954 2,785,355 Gugelberg Mar. 12, 1957 2,790,110Applegate Apr. 23, 1957

